The present invention relates to a method and a system for emergency evacuation of building occupants and to a method for modernization of an existing building with the system that allows the use of an elevator as a means of reliable egress and evacuation during emergency of a multi-story building having a plurality of floors.
Traditionally, an elevator is not considered as a reliable means of egress during a building fire. Notices like “Do not use elevator in case of fire” can be found commonly to notify the building occupants to refrain from using the elevator and to use instead a stairway.
European standard EN81-73 provides a regulation for a safe and reliable egress and evacuation during fire in a building by using an elevator. The elevator comprises a fire alarm function, which is initiated by a fire alarm system. Dependent upon the fire alarm system and the management of the fire alarm, different reactions of the elevator are foreseen. For example, after sent into fire alarm condition, the landing and car call buttons are rendered inoperative and the elevator car is automatically recalled to a designated floor of the building. The elevator is parked with the doors open and the elevator is temporarily taken out of service. Then, the fire department can override the fire alarm function by activating a fire department key switch to utilize the elevator car individually.
EN81-73, however, does not deal with the ongoing use of the elevator after a fire has been detected and will be fought. Especially in buildings with more than six floors, the fire department personnel must use also the stairway to advance on the fire and will be hindered by people, who are escaping by using the stairway. Also, EN81-73 does not refer to the generally unsafe environment for building occupants, such as smoke, heat and/or water in the building. In particular, the unsafe environment concerns the hoistway, the landing doors and the stairway. One significant reason that an elevator may not be used for emergency egress during a building fire is the danger presented by smoke. Smoke at the hoistway door will be interpreted by the elevator control as an obstacle, preventing thereby the door from closing properly. Smoke also contains toxic gases and combustion products, which create an untenable environment for people and expose them to increased risk. Water from automatic fire sprinklers or from fire department hoses can enter the hoistway and short circuit the car controls. Moreover, not only young and healthy but also non- ambulatory and disabled people search egress from the building. These building occupants cannot use the stairway and are, therefore, forced to remain in the burning building until rescued by the fire department. Finally, EN81-73 does not consider the chaotic environment and irrational psychological reactions of the building occupants, which increases the time required to evacuate the building and results in panic and injury to themselves and others.
U.S. Pat. No. 6,000,505 refers to a multiple level building with an elevator operable as a means of emergency egress and evacuation during a fire accident, which overcomes some of the before-mentioned problems and provides benefits. U.S. Pat. No. 6,000,505 discloses a system characterized by the use of smoke detectors, which is limited to the case of fire and does not consider other emergency situations requiring an evacuation with elevators, such as bomb scare, terrorist attack, hurricane, flood, or an earthquake. Furthermore, this system is automatic, but not intelligent and cannot take into account how many people are waiting to be saved on a determined floor and whether among these people some are handicapped. Moreover, this system is not flexible and not able to calculate special and faster strategies to evacuate all people in a building with the elevator. A further shortcoming of this system is that it does not consider the irrational psychological reactions of people submitted to a highly stressful emergency situation. Because an elevator is conceptualized as unsafe during emergencies, the use of an elevator during an emergency is likely to be perceived as high risk. People will, therefore, refrain from using the elevator. Moreover, a sign placard located within the elevator car and at each elevator lobby, such as shown by FIG. 8 of U.S. Pat. No. 6,000,505 is clearly insufficient to guide panicked people into an elevator during an emergency situation.